利用多次扰动电流波形特征的配电网相间永久故障识别方法

Identification method for an interphase permanent fault in a distribution network using waveform characteristics of multiple disturbance currents

针对配电网相间故障后自动重合闸盲目重合于永久性故障的问题,提出一种利用多次扰动电流波形特征的配电网相间重合前永久故障识别方法。配电线路相间故障三相跳闸后,依次对3个相间回路施加高频电压扰动。永久故障时故障相间回路、非故障相间回路均包含过渡电阻支路,而瞬时故障熄弧后即无故障时各相间回路均不受过渡电阻支路影响,永久故障和瞬时故障时对应的相间回路扰动电流的波形存在显著差异,利用该差异进行相间回路状态甄别。进一步利用Hausdorff距离系数H表征扰动电流波形的差异,若在判别周期内多次扰动电流的波形高度一致,即H值接近于0,则判为相间永久性故障。并构造了基于Hausdorff距离系数的永久故障识别判据和实现方案。PSCAD/EMTDC仿真计算与实验验证结果表明,该方法可有效判别永久性故障,并且基本不受过渡电阻、故障位置的影响。

There is a problem of blind reclosing to permanent interphase faults in distribution networks.Thus a method for identifying the permanent faults before the interphase reclosing is proposed.This is based on the characteristics of multiple disturbance current waveforms.After the three-phase tripping of the distribution line with an interphase fault,a high-frequency voltage excitation is applied to the three interphase circuits successively.In the case of a permanent fault,both the fault and non-fault interphase circuits contain a transition resistance branch.However,when there is no fault after the transient fault is extinguished,the interphase circuits are not affected by the transition resistance branch.Additionally,the waveforms of the disturbance currents in the different circuits mentioned above are distinct,and the waveform difference is used to detect the condition of the interphase circuits.Then the Hausdorff distance coefficient H is used to characterize the difference of disturbance current waveforms,and if the waveforms of multiple disturbance currents are highly consistent during the judgment period,that is,the H value is close to 0,then it is judged as a permanent interphase fault.A permanent fault identification criterion using the Hausdorff distance coefficient and a corresponding implementation scheme are constructed.The simulation results of PSCAD/EMTDC and experiments show that the method can effectively identify permanent faults,and is independent of transition resistance and fault location.